TF2 Character Personalities
If I were to rank the characters from normal to deranged and crazy.

Engineer seems to be the most normal.
Scout is normal, but is just a d-bag.
The Sniper is okay, aside from the Jarate thing.
The Demoman is a drunk.
The spy, where do I begin with him.
The Soldier is a right-wing Patton-era nutcase.
Heavy is borderline mentally challenged
The Medic is a maniacal doctor.
The Pyro, well you saw the video.